As a photoelectric conversion device used for a solar cell that converts the energy in sunlight into electrical energy, there is a known thin-film silicon photoelectric conversion device having a photoelectric conversion layer fabricated by forming thin films of a p-type silicon semiconductor (p-layer), an i-type silicon semiconductor (i-layer), and an n-type silicon semiconductor (n-layer) by using a plasma CVD method or the like.
In general, when crystalline silicon is used for the i-layer, crystalline silicon is often used for the n-layer, as in PTL 1; however, amorphous silicon may also be used therefor.
Thin-film silicon solar cells have the advantages that the area thereof can be easily increased, and only a small amount of material is used because the film thickness thereof is about one hundredth of that of crystalline solar cells. Therefore, thin-film silicon solar cells can be fabricated at lower cost than crystalline solar cells. However, thin-film silicon solar cells have the disadvantage that the conversion efficiency thereof is lower than that of crystalline solar cells. In this technical field, an improvement in the conversion efficiency is a key issue.